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Messages - Jack1962

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Amplifier Discussion / Re: Light Bulb Limiter
« on: June 23, 2014, 12:51:53 PM »
Be using a Light Bulb Limiter for years , sure saves on fuses lol

Amplifier Discussion / Re: Marshall Valvestate 8040
« on: June 23, 2014, 12:48:53 PM »
1st the voltage on those TLO72 should be around -/+14 to 16 volts (at least they have been on all of them I have worked on) VR1 should not have any DC voltage on it . check your caps I'm sure the 1 before it is bad at least , replace IC3 , as far as the 9 volts goes it's a issue but not a severe on TLO72's will operate wil a voltage as low as 5 volts.

Amplifier Discussion / Re: Scheematic for a Mesa Basis M-2000
« on: January 22, 2014, 12:08:17 PM »
Mesa sent me the service manual for this amp , I would upload it but for some reason the system won't let me so if anyone needs this schematic you"ll have to email me.

Amplifier Discussion / Scheematic for a Mesa Basis M-2000
« on: January 20, 2014, 06:05:20 PM »
anyone have the schematic for this puppy?

Tubes and Hybrids / Re: 18w minimalist
« on: August 12, 2013, 07:20:30 AM »
You are "wasting" a triode by using them in parallel.
Build a conventional, 2 triode preamp and you will have *a lot* of gain.
Check the Marshall 18W, or similar amps.

A common mod to Marshall JMP's is to parallel V1
 on this circuit I see a 1meg pot on the grid of V1 that I would guess is the pre and the other pot is your post . just to answer  the question that was ask to begin with

Tubes and Hybrids / Re: Low Voltage Tube Preamp
« on: August 12, 2013, 07:12:49 AM »
to use low( under 160 volts) you will have to use tubes that where used in things such as car radio's . However on this subject I agree with Roly , the voltage isn't your worry current is and "most" tube amp circuitry is low current. Not to offend anyone on this forum but Hoffman's form would be a better source of info on this subject.

Tubes and Hybrids / Re: Another cool but dangerous antique
« on: August 12, 2013, 07:01:57 AM »
I am unable to view the pictures you posted , which Teisco Audition is this , several where made?

Tubes and Hybrids / Re: Silvertone 1330 Widowmaker
« on: August 12, 2013, 06:51:00 AM »
Quote from: Jack1962
the first thing to do is install a grounded cord.
I would yes recommend a isolation transformer (not absolutely needed though)

Sorry Jack, ground the chassis then plug the cord in so the active is on the chassis (e.g. a transposed outlet) and you'll blow the mains circuit protection, or maybe start a fire.  Encounter an outlet which is both transposed and has an open earth (not unknown, and particularly at venues) and you're dead.

As a tech with over fifty years experience I flatly reject your advice as dangerous - an isolation transformer is absolutely needed to safely operate this amplifier, otherwise a guitarists is quite literally taking their life in their hands every time they touch their guitar.

So called "universal" appliances of this sort are abominations that should never have been built or sold in the first place, and in many parts of the world are now rightly illegal.  Adding an isolation transformer will not alter the tone in any way and will make the amp what it should always have been.

As a tech for over 35 years myself , I have grounded these amps , a real tech ALWAYS , finds a way to ground ANY piece of equipment they work or they will wind up DEAD

Tubes and Hybrids / Re: Mosvalves?
« on: August 03, 2013, 05:47:19 PM »
962 is your best bet , if you can't heard over your drummer then throw some pillows in his kettles lol

Tubes and Hybrids / Re: Silvertone 1330 Widowmaker
« on: August 03, 2013, 05:35:24 PM »
The Silvertone 1330 is a great amp if you know what your doing with it (like most any other amp).

the first thing to do is install a grounded cord.
I would yes recommend a isolation transformer (not absolutely needed though)
change out the speaker with a good Celestion or Jensen Speaker.
the tweak for tone from this point.

retension that loose socket that's your problem

Amplifier Discussion / Re: Watts vs Volume (db)
« on: April 02, 2013, 07:27:13 PM »
The output impedance from the tube is between 3k ohms and 8k ohms depending on what tube you are using. however I agree with most of what you are saying , the real difference is drum roll please , the tube is indeed a constant current source due to the output transformer , the transistor amp has it's signal dump directly onto the speaker. Myself I have and use both types tube and solid state I prefer the solid state for keys because the amp I'm using is a Peavey Musician you can use it for anything , best frequency response I have ever seen from a stock production amp. for guitar and bass I usually use tube amps because of the output power , I generally don't use anything larger than a 50 watt guitar amp for Bass I use my vintage Ampeg SVT with a 8x10 cab and a 15 jensen that I really don't remember where it came from I"ll put it up against any 500-1000 watt bass rig anytime lol

Tubes and Hybrids / Re: Is the reverb on tube amps any good?
« on: April 02, 2013, 07:10:03 AM »
Yes , the reverb on tube amps is very good ( on most of them) .

LJN what it sounds like to me that you want is a Marshall with reverb , here's what you can do , what I have done.

Find a Peavey Triumph and do some simple tone mods ( you can do this with 4 very simple mods).

INSTANT JCM800 WITH REVERB plus a better clean channel lol

Amplifier Discussion / Re: Watts vs Volume (db)
« on: April 02, 2013, 06:48:10 AM »
Great explantions on this subject  :dbtu:

I love hearing JM and Joe lay the info down for ya , so here's a twist to this , why is a lower wattage tube amp louder than higher wattage solid state amp , thru the same speaker.

Great Answers Roly,

Mexicanyella , here's what you need if yo want to play guitar and bass (or anything else) thru the same amp and cabs , buy a power amp (PA) buy monitor cabs not instrument amp cabs power amps just amplify they do care what the source is , monitor cabs have better frequency response .

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